The Eclipse Debug Project is not a single project unto itself, it is in fact comprised of two distinct components: Platform Debug and JDT Debug.

Platform Debug defines interfaces for a language independent debug model which abstract common debugging features of many languages, whereas, JDT Debug provides an implementation of platform debug providing Java debugging support and works with any JDPA-compliant target Java VM.

Both Platform and JDT Debug are built into Eclipse and ship as part of the Eclipse SDK.